[FFmpeg-devel] [PATCH 1/3] avcodec/vp56: Require 1 undamaged frame for 5 damaged frames for concealment to be used

[Ronald S. Bultje]

Hi,

On Wed, Mar 15, 2017 at 8:21 AM, Kieran Kunhya <kierank at obe.tv> wrote:

> On Wed, 15 Mar 2017 at 12:05 Ronald S. Bultje <rsbultje at gmail.com> wrote:
>
> > Hi,
> >
> > On Tue, Mar 14, 2017 at 11:12 PM, Michael Niedermayer <
> > michael at niedermayer.cc> wrote:
> >
> > > Fixes timeout with 847/clusterfuzz-testcase-5291877358108672
> > > Fixes timeout with 850/clusterfuzz-testcase-5721296509861888
> > >
> > > This likely will need to be tweaked
> >
> >
> > Sorry, but this is getting insane. I can't possibly be expected to just
> > approve this. What's your end game?
> >
>
> I have tons of testcases for h264 that are 1KB and can make error
> concealment run for ages.
> Trying to fix them will just become a never ending set of heuristics to
> guess the conditions like the above.


Right. Also, this is fuzz-specific code. I've made remarks about this
before, but I'll say it again: ideally, I don't want fuzz-specific code
anywhere. Especially not "carefully crafted" crap like this.

I'm actually starting to believe that the error concealment code in this
decoder (vp56) is fuzz-specific code also. Is there a real-world input
where the user experience is improved by this code?

(If you want to speed up fuzzing, just add an artificial resolution limit
of 64x64 in your fuzzing binary's get_buffer2() callback.)

Ronald